Conventionally, silk or cotton has been used as cloth from which cotton or down is restrained from spouting out, which is used for outerwear or Japanese bedding (futon) side cloth, since it is excellent in feeling or comfortableness.
However, cloth made of a natural fiber is low in tear strength and poor in durability; therefore, when the cloth is used particularly for outerwear, there is caused a problem that cotton or down spouts out easily from an elbow or sleeve portion thereof.
A polyester multifilament, a nylon multifilament and a composite synthetic fiber fabric thereof have also been used in many cases since mechanical properties thereof are excellent. These synthetic fiber fabrics are frequently used particularly for coats, blousons, golf and outdoor wears, and so forth since they are soft, light, windproof, highly water-repellent, and highly strong. For example, an attempt has been made for raising the strength of a polyamide filament in order to obtain a fibrous product for which tear strength is required (see, for example, Japanese Patent Application Laid-Open No. 2003-55859), and there is disclosed a method of raising the draw ratio thereof to give polyamide filaments having a high strength. However, about such a yarn, the strength thereof becomes high when it is lengthened by 10%. Thus, conversely, the elongation percentage becomes low so that the feeling of the fabric becomes hard. When the elongation percentage becomes low, the following is caused through the process wherein the fabric is torn: the number of yarns subjected to the tearing becomes small, so that stress concentrates easily onto any one of the yarns. Thus, conversely, the tear strength becomes low. This case is not favorable. When yarn having a large linear density is used to heighten the tear strength of the fabric, the fabric becomes thick. Thus, the feeling thereof becomes hard, and the fabric is unsuitable for articles which are required to be stored in a compact form, such as a tent, a paraglider, and a parachute.
Even about fabrics wherein a synthetic fiber is used, the weft tear strength becomes relatively low on the basis of the weft weave density thereof. Thus, in order to set the weft tear strength to 10 N or more, it is indispensable to set the weave density of the warp or weft thereof per 2.54 cm to a small value. For example, about 33 dtex nylon filaments, it is necessary to set the total number of the yarns for the warp and weft to 280 or less per 2.54-cm (see, for example, Japanese Patent Application Laid-Open No. 11-247022). In order to make air permeability low, fabrics having a plain weave design have hitherto been developed. However, these cannot have a sufficient tear strength if the linear density thereof is not set to 44 dtex or more. Thus, a fabric which satisfies all of lightness, low air permeability and high tear strength at a high level has not been developed.
An object of the present invention is to solve the above-mentioned problems in the prior art; and to provide a fabric which is excellent in all of lightness, low air permeability and high tear strength and which can be used particularly as a down proof cloth of a down jacket, and a production process thereof.